Improvement in electrical circuit-closers



L. L. DUERDEN.

Electrical Circuit-Closer.

No 6 3 753, Patented May 25,1875.

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UNITED STATES PATENT OFFICE.

LAWRENCE L. DUERDEN, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN ELECTRICAL CIRCUIT-CLOSERS.

Specification forming part of Letters Patent No. 163,753, dated May 25,1875 application filed May 8, 1875.

To all whom it may concern Be it known that I, LAWRENCE LOUIS DUERDEN,of the city of Brooklyn, State of New York, have invented certain newand useful Improvements in Keys for Telegraphic and other ElectricalInstruments, of which the following is a specification:

My invention consists of a telegraph-key of a novel structure. Themoving part of the key, or that part by the movement of which contact ismade and broken, consists of an elastic and flexible disk or diaphragmsecured at its edges, and so formed that when pressed in one directionby the hand or other power, it will, by its own elasticity, whenrelieved of that pressure, recoil and resume its normal position. Thisdisk is mounted on a non-conducting base, preferably of hard rubber orof some composition easily molded. The base is formed on top with anannular groove or recess, and the disk is secured at its edges to thebody of the base, its edges entering the annular recess, and the jointbeing sealed with varnish or otherwise, thus constituting, with thebase, the walls of a hermeticallysealed or airtight chamber, in whichare placed the contact points. These points are in this way sealed andprotected against any chemical or mechanical action of the atmosphere,rain, moisture, or dust, and thus preserve unimpaired their 'efliciencyas circuitclosers.

The elastic disk is preferably made of metal, and may, in itself, whenbrought in contact with the contact-point in the base, form part of thecircuit; or it may be made of other suitable material, and provided witha contact-point having suitable connections to complete the circuit whenthe disk is depressed.

The nature of my invention and the manner in which the same is or may becarried into effect will be understood by reference to the accompanyingdrawing, in which I have represented one form of my improved key.

Figure 1 is a perspective view of the key. Fig. 2 is a vertical centralsection of the same.

A is the base formed with a flange, a, by which it may be secured to theoperating-table, and with a recess or annular depression, I), in itstop. It also has a recess, 0, in its bottom to receive the screw d,which is inserted centrally in the base, and extends up therethroughinto the recess 12. Over the base A is placed the elastic and flexiblemetallic disk or diaphragm B, secured by its edges to the walls of therecess 12, and provided on its under face with a central contactpoint,j, which comes directly opposite the contact-point on the end of screw(Z. This screw can be set nearer to farther from the disk, as described,in order to set the contactpoints at the proper distance apart. Oneterminal wire, g, connects with the disk, the other, h, with the screw.When the disk B is depressed the contact-points will meet, and thecircuit will be completed through the disk and screw. When, on the otherhand, the disk isrelieved from pressure, it will, by its own elasticity,recoil and resume its normal position.

Under the arrangement shown it will be noted that the contactmints areinclosed in a hermetically-sealed chamber, with the resulting advantagesabove indicated.

Having described my invention and the manner in which the same is or maybe carried into effect, what I claim, and desire to secure by LettersPatent, is-

1. A telegraph-key, the moving part of which (for making and breakingcontact) consists of a flexible and elastic diaphragm or disk, securedat its edges to a suitable base, and operating substantially as hereinshown and described.

2. The combination of the flexible and elastic metallic diaphragm ordisk, the recessed base, to which said diaphragm is secured at itsedges, and the contact-points, inclosed in a chamber formed by andbetween the disk and base, substantially as set forth.

3. A telegraph-key, in which the contactpoints are contained in achamber hermetically sealed, or practically so, to the atmosphere,substantially as set forth.

In testimony whereof I have hereunto signed my name this 30th day ofApril, A. D. 1875.

L. L. DUERDEN.

Witnesses:

JAMES F. ABRAMS, GEORGE W. AsroN.

